K-Factor (Virality)
A measure of how many new users each existing user generates through referrals.
The K-factor quantifies viral growth: a K above 1 means each user brings more than one new user, creating self-sustaining growth. Built-in sharing, referrals and network effects drive it. Even sub-viral loops meaningfully lower acquisition costs.
Examples
A referral programme pushes the K-factor toward 1. — A product’s sharing loop drives organic growth.
How it relates to The Startup Foundry
Viral or referral-driven growth strengthens Scalability — a core pillar of the Investability Report.